Biology Essays Heart Disease

Biology Essays substance DiseaseThe Biological Basis and Risk Factors for coronary thrombosis Heart Disease.Coronary marrow squash sickness is a blanket endpoint which describes all types of intent disease wee-weed by blockage of the arteries that supply ocellus to the heart. Lack of sufficient roue is associated with a lack of oxygen, also called ischemia. Hence coronary heart disease is also called ischemic heart disease. Angina, heart attack and heart failure and ar all clinical forms of coronary heart disease.1Overall, coronary heart disease is the leading cause of death in the Western world.2 In the UK, heart attacks are responsible for around 150,000 deaths every year and fol grim the NHS approximately 719 million per year. Almost half of all heart attack sufferers die inwardly 20 days of the attack.3The heart of the problemThe heart is a vital organ, pumping kin which carries essential oxygen and nutrients all around the body. As a powerfully active muscle, the heart needs a ready and racy supply of oxygen and nutrients itself however these are not extracted from the blood that flows through it. Instead, the heart has its own specific blood supply the coronary arteries. thither are two major coronary arteries the right and left. The volume of blood which flows to the heart is largely determined by the width of these vessels and is not so dependent on the power at which the blood is pumped through them. Unlike other organs which can use the oxygen indoors veins if needed, the heart is completely reliant on the coronary arteries supply. Hence their ability to expand and supply more blood when required is essential.4-6Coronary heart disease develops when various materials build up inside the walls of the coronary arteries causing a narrowing of the vessels and potentially leading to complete blockage. The obstruction of blood flow to the heart which results from this build up within the coronary arteries can cause a range of cardiac probl ems. When the blood flow to the heart is only temporarily interrupted, unremarkably during exercise and times of execution when the heart muscle requires more oxygen, the condition is known as angina. A person with angina testament experience short attacks of chest pain which usually clear up with rest. Ultimately, insufficient blood flow can result in actual physical damage to the heart tissue. In severe cases, where blood flow is completely blocked, the portion of the heart affected may die from lack of oxygen this is termed myocardial infarction, commonly known as a heart attack. Symptoms of heart attack include prolonged and severe chest pain, weakness and shortness of breath. In rare cases, patients with coronary heart disease experience heart failure. This is a broad condition which describes any symptoms showing that a patients heart is not performing as it should. 4-6Why do coronary arteries plough blocked?In healthy arteries, the walls are smooth and blood flows easily. The process leading to the development of coronary heart disease begins with the development of productive streaks. These are yellow patches which appear within the wall of the coronary arterial blood vessel. The streaks are made up of a special type of cell called foam cells, which are rich in fats, plus smooth muscle cells. Over time, streaks can turn into plaques. Plaques, also known as atheroma, are fatty lumps which form within the lining of the arteries. There are various different kinds of plaques. Some are made up of a soft inner force of cholesterol cover by a thin firm outer layer. Others are completely solid and composed of smooth muscle cells and various other strong materials. calcium may also build up on a plaque making the problem worse.4,7What is the blockage like?Plaques cause several problems to coronary blood flow. Firstly, a plaque itself can be big enough to narrow the artery and reduce the space available for blood to flow through it. Secondly, as blood is t hrust against the side of the plaque with from each one heart beat, the outer shell of the plaque may crack open exposing the cholesterol core. When the cholesterol core is exposed, blood coagulate is triggered within the artery. Clots reduce the blood flow even more. This whole process can happen repeatedly causing the artery to become narrower and narrower and eventually leading to complete blockage.4,7Overall, the process of plaque formation and associated thickening, loss of elasticity and narrowing of the artery walls is known as coronary artery disease. Atherosclerosis is the major cause of coronary heart disease however, it is also present to some degree in almost every adult male in Western societies. What causes atherosclerosis to occur is complex and uncertain and there is much still to learn. Current thinking is that atherosclerosis results from some kind of response to suffering where initial non-specific injury to the lining of the artery wall triggers the whole pro cess to start up.4,7,8Risk factor insEveryone has some disaster of experiencing heart disease, however, various factors have been identified which increase the take chances of developing coronary heart disease. These include4,6,7,8High cholesterolSmokingLack of exerciseUnhealthy dietObesityDiabetesHigh blood constrict (hypertension)Mental stressHigh levels of certain blood clotting factorsFamily historyAlcohol and coffeeMale genderEthnic group (e.g. Southern Asians in the UK are at higher risk)Most of these risk factors increase the risk of coronary heart disease by increasing the likelihood that atherosclerosis will develop within the coronary arteries themselves. Also, these risk factors have been found to interact. Hence if you have two or more risk factors your overall chance of developing coronary heart disease is proportionally higher than if you just had one risk factor.8Heredity as a risk factorCoronary heart disease often occurs within several members of the same family , indicating that a genetic link may be involved. However, it is difficult to determine if the link amidst family members is due to genes or shared environmental factors, such as diet and exposure to smoke. Genetic factors have been shown to influence cholesterol levels and the amount of blood clotting factors a person has in their blood, which in turn has a knock-on effect on the risk of developing atherosclerosis. Overall, it seems that a combination of genetics and the environment would surpass explain the family link to heart disease. It has been estimated that 40% of the risk is controlled by genes, and 60% is due to environmental factors.4,6High cholesterol as a risk factorThere are two types of cholesterol found in the blood good HDL cholesterol which can protect against the development of heart disease and bad LDL cholesterol which promotes the development of atherosclerosis. There is lots of evidence to show that unhealthy amounts of these two types of fat in the blood, i.e. high LDL and low HDL levels, can increase the chance of developing coronary heart disease. This is because high levels of cholesterol in the blood encourage the formation of plaques within the artery wall and promote the overall process of atheroschlerosis.4,6The cause of high LDL levels has not been clearly established but dietary factors are likely to be involved. There is evidence that a diet high in saturated, but lacking in polyunsaturated, fat may contribute to high cholesterol levels. There is relatively little actual cholesterol in the diet, but saturated fat is converted into cholesterol in the liver.4,6Lack of exercise as a risk factorLack of exercise is a proven risk factor for the development of coronary heart disease. Overall, the risk is a third little in people who exercise compared to those who dont.8 It seems that physical exercise has a protective effect on the development of coronary heart disease. The mechanism vestigial this has not been fully elucidated but certain hypotheses have been put forward. Exercise may increase levels of good HDL cholesterol and also reduce the blood clotting which occurs within atherosclerotic arteries and causes further blockage. Exercise might also help enlarge the coronary arteries and hence increase blood supply to the heart. In order to gain full health benefits from exercise in the reduction of coronary heart disease risk, five bouts of moderate physical activity per week, each lasting a minimum of 30 minutes, are recommended.ConclusionCoronary heart disease is a serious condition caused by the build-up of fatty deposits within the walls of the vital arteries that supply blood to the heart. Coronary heart disease is the major cause of death in Western societies but to a large limit is preventable. Recognising the key risk factors which contribute to the development of atherosclerosis is an important step towards reducing the overall incidence of coronary heart disease.ReferencesWalton J, Beeson PB, Bodley Scott R, 1986. The Oxford Companion to Medicine flock I, A-M. Oxford Oxford University Press.Higgins M, 2001. Patients, families and populations at high risk for coronary heart disease. European Heart Journal, 22 1682-1690.Association of the British Pharmaceutical Industry, 2005. Hitting the Target Medicines and Coronary Heart Disease and Stroke. Available at http//www.abpi.org.uk/publications/publication_details/hitting_target/section5b.asp Accessed 14 March 2005.Julian DG Campbell Cowan J, 1992. Cardiology Sixth Edition. London Bailliere Tindal.Vander AJ, Sherman JH, Luciano DS, 1994. Human Physiology The Mechanisms of Body Function. International Edition McGraw-Hill.Edwards CRW Bouchier IAD (Eds), 1991. Davidsons Principles and drill of Medicine Sixteenth Edition. London Churchill Livingston.Singh VN, 2005. Coronary Heart Disease. Emedicine. Available from http//www.emedicinehealth.com/articles/10951-1.asp Accessed 14 March 2005.PRODIGY Guidance, 2004. Preventing Hear t Disease and Stroke. Patient information leaflet. Available at http//www.prodigy.nhs.uk/clinicalguidance/releasedguidance/webBrowser/pils/PL82.htm Accessed 14 March 2005.